Process for producing polycarbonate

Abstract

PCT No. PCT/JP96/00178 Sec. 371 Date Jul. 31, 1997 Sec. 102(e) Date Jul. 31, 1997 PCT Filed Jan. 31, 1996 PCT Pub. No. WO96/23832 PCT Pub. Date Aug. 8, 1996There are disclosed a process for producing a polycarbonate through transesterification which comprises using, as a polymerization catalyst, (1) a combination of a nitrogen-containing organic basic compound and a quaternary phosphonium salt, (2) a tetraarylphosphonium salt having a specific chemical structure, or (3) a quaternary phosphonium salt having a specific chemical structure and containing a branched alkyl group; and a process for producing a polycarbonate which comprises the steps of preparing a polycarbonate prepoplymer by preliminary polymerization and thereafter polymerizing the resultant prepolymer in a state of a solid phase by the use of a quaternary phosphonium salt as a catalyst. By using any of these processes it is made possible to produce, in extremely high efficiency, a high-quality polycarbonate being excellent in appearance, heat resistance, hydrolysis resistance and the like.

We claim: 
     
       1. A process for producing a polycarbonate comprising a transesterification in the presence of a polymerization catalyst which comprises a combination of (a) a nitrogen-containing organic basic compound and (b) a quaternary phosphonium salt wherein said quaternary phosphorium salt is selected from the group consisting of a compound represented by formula (II):   (PR.sup.3.sub.4).sup.+.sub.a (X.sup.2).sup.a-              (II)     wherein R 3  is an organic group, four R 3  are the same or different from each other, or two R 3  combine with each other to form a ring; X 2  is a halogen atom, hydroxyl group, (R 4  O) 2  P(═O)O in which R 4  is a hydrocarbon group, and two R 4  O are the same as or different from each other, BR 5   4  in which R 5  is a hydrogen atom or hydrocarbon group and four R 5  are the same or different from each other, HCO 3  or CO 3  ; and a is 2 in the case of X 2  being CO 3  and is 1 in the other cases; and   a compound represented by formula (III): ##STR20## wherein R 6  is an organic group, and a plurality of R 6  --Ph(Ph: phenyl group), when being present, are the same or different from each other; X 3  is a halogen atom, hydroxyl group, alkyloxy group, aryloxy group, alkylcarbonyloxy group, arylcarbonyloxy group, BR 7   4  in which R 7  is a hydrogen atom or hydrocarbon group and four R 7  are the same or different from each other, HCO 3  or CO 3  ; b is 2 in the case of X 3  being CO 3  and is 1 in the other cases; and n is an integer of 0 to 4.   
     
     
       2. The process for producing a polycarbonate according to claim 1 wherein the nitrogen-containing organic basic compound is a quaternary ammonium salt. 
     
     
       3. The process according to claim 1 wherein the nitrogen-containing organic basic compound is a quaternary ammonium salt or dimethylaminopyridine, said salt being represented by the general formula (I)   (NR.sup.1.sub.4).sup.+.sub.z (X.sup.1).sup.z-              (I)     wherein R 1  is an organic group, four R 1  are the same or different from each other, or two R 1  combine with each other to form a ring; X 1  is a halogen atom, hydroxyl group, alkyloxy group, aryloxy group, alkylcarbonyloxy group, arylcarbonyloxy group, HCO 3 , CO 3 , or BR 2   4  in which R 2  is a hydrogen atom or hydrocarbon group and four R 2  are the same or different from each other; and z is 2 in the case of X 1  being CO 3  and is 1 in the other cases.   
     
     
       4. The process for producing a polycarbonate according to claim 1 wherein the component (a) is tetramethylammonium hydroxide and the component (b) is selected from the group consisting of tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium phenolate and tetraphenylphosphonium hydroxide. 
     
     
       5. The process for producing a polycarbonate according to claim 1 wherein the component (a) is tetramethylammonium hydroxide and the component (b) is at least one compound selected from the group consisting of biphenyltriphenylphosphonium tetraphenylborate,   phenoxyphenyltriphenylphosphonium tetraphenylborate,   methoxyphenyltriphenylphosphonium tetraphenylborate,   biphenyltriphenylphosphonium phenoxide,   phenoxyphenyltriphenylphosphonium phenoxide and   methoxyphenyltriphenylphosphonium phenoxide.   
     
     
       6. The process according to claim 1 wherein the quaternary phosphonium salt is a quaternary phosphonium salt containing a branched alkyl group. 
     
     
       7. The process according claim 6 wherein the quaternary phosphonium salt containing a branched alkyl group is a compound represented by the general formula (IV) ##STR21## wherein R 8 , R 9  and R 10  are each a hydrogen atom, alkyl group or aryl group, and are the same as or different from each other, or at least two of them combine with each other to form a ring, but two or three of them are not simultaneously a hydrogen atom, a plurality of R 8  R 9  R 10  C--, when being present, are the same as or different from each other; R 11  is an alkyl group or aryl group and a plurality of R 11 , when being present, are the same as or different from each other; X 4  is a halogen atom, hydroxyl group, alkyloxy group, aryloxy group, alkylcarbonyloxy group, arylcarbonyloxy group, BR 12   4  in which R 12  is a hydrogen atom or hydrocarbon group and four R 12  are the same as or different from each other, HCO 3  or CO 3  ; C is 2 in the case of X 4  being CO 3  and is 1 in the other cases; and m is an integer of 1 to 4. 
     
     
       8. The process according to claim 1 wherein the starting raw materials for the transesterification are (A) a dihydroxy compound and (B) a carbonic acid diester. 
     
     
       9. A process for producing a polycarbonate through transesterification which comprise using, as a polymerization catalyst, a quaternary phosphonium salt represented by the general formula (III): ##STR22##10. 
     
     
       10. The process according to claim 9 wherein the quaternary phosphonium salt is at least one member selected from the group consisting of biphenyltriphenylphosphonium tetraphenylborate, biphenyltriphenylphosphonium phenoxide, phenoxyphenyltriphenylphosphonium tetraphenylborate, phenoxyphenyltriphenylphosphonium phenoxide, methoxyphenyltriphenylphosphonium tetraphenylborate and methoxyphenyltriphenylphosphonium phenoxide. 
     
     
       11. The process according to claim 9 wherein the starting raw materials for the transesterification are (A) a dihydroxy compound and (B) a carbonic acid diester. 
     
     
       12. A process for producing a polycarbonate through transesterification which comprises using, as a polymerization catalyst, a quaternary phosphonium salt containing a branched alkyl group. 
     
     
       13. The process according to claim 12 wherein the quaternary phosphonium salt containing a branched alkyl group is a compound represented by the general formula (IV): 
     
     
       14. The process according to claim 12 wherein starting raw materials for the transesterification are (A) a dihydroxyl compound and (B) a carbonic acid diester. 
     
     
       15. A process for producing a polycarbonate which comprises the steps of preparing a polycarbonate prepolymer by preliminary polymerization and thereafter polymerizing said polycarbonate prepolymer in a state of a solid phase by the use of a quaternary phosphonium salt as a catalyst. 
     
     
       16. The process according to claim 15 wherein said polycarbonate prepolymer is prepared by subjecting a dihydroxy compound and a carbonic acid diester to transesterification. 
     
     
       17. The process according to claim 15 wherein said polycarbonate prepolymer is prepared by the use of a nitrogen-containing organic basic compound as a catalyst. 
     
     
       18. The process according to claim 15 wherein said polycarbonate prepolymer is prepared by subjecting a dihydroxy compound and phosgene to interfacial polycondensation. 
     
     
       19. The process according to claim 15 wherein said polycarbonate prepolymer is polymerized in a state of a swelling solid phase in the presence of a quaternary phosphonium salt as a catalyst in an atmosphere of a gas selected from the group consisting of (a) a swelling solvent gas, (b) a mixed gas of a swelling solvent gas with a poor solvent gas, (c) a mixed gas of a swelling solvent gas with an inert gas and (d) a mixed gas of a swelling solvent gas with an inert gas and a poor solvent gas. 
     
     
       20. The process according to claim 15 wherein a granulated spherical polycarbonate prepolymer is polymerized in a state of a solid phase in the presence of a quaternary phosphonium salt as a catalyst, said prepolymer being granulated by feeding a solution of a polycarbonate prepolymer in an organic solvent to a granulating vessel containing a powdery polycarbonate prepolymer which has been stirred in advance, and evaporating said organic solvent while said solution of a polycarbonate prepolymer in said organic solvent is brought into contact with said powdery polycarbonate prepolymer. 
     
     
       21. The process for producing a polycarbonate according to claim 1 characterized in that the produced polycarbonate has a rate of decrease in molecular weight of at most 10% in a steam resistance test.